Exiv2::CommentValue Class Reference

Value for an Exif comment. More...

#include <value.hpp>

Inheritance diagram for Exiv2::CommentValue:

Classes

class  CharsetInfo
 Charset information lookup functions. Implemented as a static class. More...
 
struct  CharsetTable
 Information pertaining to the defined character sets. More...
 

Public Types

enum  CharsetId {
  ascii, jis, unicode, undefined,
  invalidCharsetId, lastCharsetId
}
 Character set identifiers for the character sets defined by Exif.
 
typedef std::auto_ptr
< CommentValue
AutoPtr
 Shortcut for a CommentValue auto pointer.
 
- Public Types inherited from Exiv2::StringValueBase
typedef std::auto_ptr
< StringValueBase
AutoPtr
 Shortcut for a StringValueBase auto pointer.
 
- Public Types inherited from Exiv2::Value
typedef std::auto_ptr< ValueAutoPtr
 Shortcut for a Value auto pointer.
 

Public Member Functions

Creators
 CommentValue ()
 Default constructor.
 
 CommentValue (const std::string &comment)
 Constructor, uses read(const std::string& comment)
 
virtual ~CommentValue ()
 Virtual destructor.
 
Manipulators
int read (const std::string &comment)
 Read the value from a comment. More...
 
int read (const byte *buf, long len, ByteOrder byteOrder)
 Read the comment from a byte buffer.
 
Accessors
AutoPtr clone () const
 
long copy (byte *buf, ByteOrder byteOrder) const
 Write value to a character data buffer. More...
 
std::ostream & write (std::ostream &os) const
 Write the comment in a format which can be read by read(const std::string& comment).
 
std::string comment (const char *encoding=0) const
 Return the comment (without a charset="..." prefix) More...
 
const char * detectCharset (std::string &c) const
 Determine the character encoding that was used to encode the UNICODE comment value as an iconv(3) name. More...
 
CharsetId charsetId () const
 Return the Exif charset id of the comment.
 
- Public Member Functions inherited from Exiv2::StringValueBase
 StringValueBase (TypeId typeId)
 Constructor for subclasses.
 
 StringValueBase (TypeId typeId, const std::string &buf)
 Constructor for subclasses.
 
 StringValueBase (const StringValueBase &rhs)
 Copy constructor.
 
virtual ~StringValueBase ()
 Virtual destructor.
 
AutoPtr clone () const
 
virtual long count () const
 Return the number of components of the value.
 
virtual long size () const
 Return the size of the value in bytes.
 
virtual long toLong (long n=0) const
 Convert the n-th component of the value to a long. The behaviour of this method may be undefined if there is no n-th component. More...
 
virtual float toFloat (long n=0) const
 Convert the n-th component of the value to a float. The behaviour of this method may be undefined if there is no n-th component. More...
 
virtual Rational toRational (long n=0) const
 Convert the n-th component of the value to a Rational. The behaviour of this method may be undefined if there is no n-th component. More...
 
- Public Member Functions inherited from Exiv2::Value
 Value (TypeId typeId)
 Constructor, taking a type id to initialize the base class with.
 
virtual ~Value ()
 Virtual destructor.
 
virtual int setDataArea (const byte *buf, long len)
 Set the data area, if the value has one by copying (cloning) the buffer pointed to by buf. More...
 
TypeId typeId () const
 Return the type identifier (Exif data format type).
 
AutoPtr clone () const
 Return an auto-pointer to a copy of itself (deep copy). The caller owns this copy and the auto-pointer ensures that it will be deleted.
 
std::string toString () const
 Return the value as a string. Implemented in terms of write(std::ostream& os) const of the concrete class.
 
virtual std::string toString (long n) const
 Return the n-th component of the value as a string. The default implementation returns toString(). The behaviour of this method may be undefined if there is no n-th component.
 
virtual long sizeDataArea () const
 Return the size of the data area, 0 if there is none.
 
virtual DataBuf dataArea () const
 Return a copy of the data area if the value has one. The caller owns this copy and DataBuf ensures that it will be deleted. More...
 
bool ok () const
 Check the ok status indicator. After a to<Type> conversion, this indicator shows whether the conversion was successful.
 

Public Attributes

ByteOrder byteOrder_
 Byte order of the comment string that was read.
 
- Public Attributes inherited from Exiv2::StringValueBase
std::string value_
 Stores the string value.
 

Additional Inherited Members

- Static Public Member Functions inherited from Exiv2::Value
static AutoPtr create (TypeId typeId)
 A (simple) factory to create a Value type. More...
 
- Protected Member Functions inherited from Exiv2::StringValueBase
StringValueBaseoperator= (const StringValueBase &rhs)
 Assignment operator.
 
- Protected Attributes inherited from Exiv2::Value
bool ok_
 Indicates the status of the previous to<Type> conversion.
 

Detailed Description

Value for an Exif comment.

This can be a plain Ascii string or a multipe byte encoded string. The comment is expected to be encoded in the character set indicated (default undefined), but this is not checked. It is left to caller to decode and encode the string to and from readable text if that is required.

Member Function Documentation

std::string Exiv2::CommentValue::comment ( const char *  encoding = 0) const

Return the comment (without a charset="..." prefix)

The comment is decoded to UTF-8. For Exif UNICODE comments, the function makes an attempt to correctly determine the character encoding of the value. Alternatively, the optional encoding parameter can be used to specify it.

Parameters
encodingOptional argument to specify the character encoding that the comment is encoded in, as an iconv(3) name. Only used for Exif UNICODE comments.
Returns
A string containing the comment converted to UTF-8.
long Exiv2::CommentValue::copy ( byte buf,
ByteOrder  byteOrder 
) const
virtual

Write value to a character data buffer.

The user must ensure that the buffer has enough memory. Otherwise the call results in undefined behaviour.

Note
The byte order is required by the interface but not used by this method, so just use the default.
Parameters
bufData buffer to write to.
byteOrderByte order. Not used.
Returns
Number of characters written.

Reimplemented from Exiv2::StringValueBase.

const char* Exiv2::CommentValue::detectCharset ( std::string &  c) const

Determine the character encoding that was used to encode the UNICODE comment value as an iconv(3) name.

If the comment c starts with a BOM, the BOM is interpreted and removed from the string.

Todo: Implement rules to guess if the comment is UTF-8 encoded.

int Exiv2::CommentValue::read ( const std::string &  comment)
virtual

Read the value from a comment.

The format of comment is:
[charset=["]Ascii|Jis|Unicode|Undefined["] ]comment
The default charset is Undefined.

Returns
0 if successful
1 if an invalid character set is encountered

Reimplemented from Exiv2::StringValueBase.


The documentation for this class was generated from the following file: